1. Field of the Invention
The present invention relates to a cellular-based wireless communication system, and more particularly to a method for allocating resources for data transmission in a cellular-based wireless communication system employing a multicarrier scheme.
2. Description of the Related Art
With the advance and ongoing demand in communication systems, the communication systems need to provide more and various types of services. Therefore, there is an earnest need for broadband communication systems capable of providing broadband services.
Frequency resources in communication systems are generally limited, and thus the broadband communication systems also have limitations on available frequency bands. Moreover, since backward compatibility with already installed communication systems must be considered, it is difficult to design the broadband communication systems.
Broadband communication systems as presently proposed are designed on the assumption that they use different frequency bands. However, with the development of communication technologies, it is inevitable that the demand for more and more frequency bands for the broadband services will increase. Consequently, license costs for the use of frequency bands are also increasing, which leads to a situation in which various schemes proposed for providing the broadband services are delayed.
There is a desire for ways to overcome limitations on the frequency bands, that is, to solve a problem of the increase in license costs for the frequency bands, and yet to favorably provide the broadband services. One of solutions is a wireless communication system employing an OFDM scheme, which reuses the same frequency bands in order to increase the efficiency of frequency use.
To this end, in the OFDM-based wireless communication system a cell is divided into a plurality of sectors, and sectors which do not neighbor each other use the same frequency bands. Thus, a resource allocation method for this may be diversely implemented by taking into consideration the channel conditions of a terminal, the type of a user channel and so forth.
In a case of reusing frequency bands, a terminal located at a cell edge is greatly influenced by interferences with a neighbor sector using the same frequency band.
FIG. 1 illustrates a cell structure with a frequency reuse factor of 2, and an example of downlink resource allocation for such a cell structure. In FIG. 1, cells 10, 20, 30 are each divided into 6 sectors. Since the frequency reuse factor is 2, the sectors are grouped into two regions (region 1 and region 2) in which frequency resources are dividedly used. That is, the respective sectors belong to any one of the regions 1 and 2, and are separated from each other such that sectors belonging to the region 1 do not neighbor sectors belonging to the region 2. Thus, the respective sectors are not theoretically influenced by other neighbor sectors.
However, a terminal located at a cell edge 40 is greatly influenced by interferences from signals of other neighbor sectors using the same frequency resource. This is because the intensity of a signal from a base station is very low at the cell edge 40, and thus the signal is difficult to discriminate from other signals of neighbor sectors using the same frequency resource.